National survey on the current practice and attitudes toward the management of chronic subdural hematoma

Abstract Background Chronic subdural hematoma (CSDH) is a frequent pathological entity in daily clinical practice. However, evidence‐based CSDH‐guidelines are lacking and level I evidence from randomized clinical trials (RCTs) is limited. In order to establish and subsequently implement a guideline, insight into current clinical practice and attitudes toward CSDH‐treatment is required. The aim is to explore current practice and attitudes toward CSDH‐management in the Netherlands. Methods A national online survey was distributed among Dutch neurologists and neurosurgeons, examining variation in current CSDH‐management through questions on treatment options, (peri)operative management, willingness to adopt new treatments and by presenting four CSDH‐cases. Results One hundred nineteen full responses were received (8% of neurologists, N = 66 and 35% of neurosurgeons, N = 53). A majority of the respondents had a positive experience with burr‐hole craniostomy (93%) and with a conservative policy (56%). Around a third had a positive experience with the use of dexamethasone as primary (30%) and additional (33.6%) treatment. These numbers were also reflected in the treatment preferences in the presented cases. (Peri)operative management corresponded among responding neurosurgeons. Most respondents would be willing to implement dexamethasone (98%) if equally effective as surgery and tranexamic acid (93%) if effective in CSDH‐management. Conclusion Variation was found regarding preferential CSDH‐treatment. However, this is considered not to be insurmountable when implementing evidence‐based treatments. This baseline inventory on current clinical practice and current attitudes toward CSDH‐treatment is a stepping‐stone in the eventual development and implementation of a national guideline.


INTRODUCTION
Chronic subdural hematoma (CSDH) is a collection of blood, blood breakdown products, and cerebrospinal fluid in the subdural space, which occurs frequently in neurological and neurosurgical practice. Worldwide, burr-hole craniostomy is the mainstay in CSDHmanagement (Kolias et al., 2014;Soleman et al., 2017). The perioperative placement of a subdural drain was the first level I evidence available in CSDH research, associated with a reduced recurrence rate and mortality at 6 months (Santarius et al., 2009). However, recent publications suggested that a subperiosteal drain leads to fewer recurrences compared to a subdural drain ( Greuter et al., 2020;Pranata et al., 2020;Soleman et al., 2019). Using a drain is beneficial, but the exact definition and way of using these two types of drains are still part of the debate on CSDH management. There is an ongoing lack of evidence-based guidelines regarding the optimal treatment for the individual patient diagnosed with CSDH. As a result, there is wide variability in the treatment of this condition. This variability is not only seen internationally, but also at a national, regional, and interhospital level, and even among treating physicians (Kolias et al., 2014). Therefore, there is an ongoing need for evidence-based guidelines in CSDH.
Especially because CSDH mainly affects elderly patients. The incidence of CSDH is expected to rise because of the large ageing population (United Nations) and the increasing use of antiplatelet agents and anticoagulants (Vacca & Argento, 2018). Therefore, complications and side effects of (non)surgical treatments must be carefully considered when creating a guideline for this fragile population.
Before establishing and implementing a guideline, barriers that can cause nonadherence to guidelines should be identified. Nonadherence to guidelines can be caused by a wide range of barriers, most prominently a lack of agreement with guideline recommendations, but also because of environmental barriers such as organizational constraints and a lack of collaboration (Lugtenberg et al., 2009). Implementation of guidelines can also be complicated by a lack of awareness of the existence of a guideline, lack of familiarity with the guideline or with the advised treatment, lack of outcome expectancy, and the inertia of previous practice (Cabana et al., 1999).
To detect and explore these barriers, which can be faced when implementing a guideline, three steps should be considered. First, it is important to understand the underlying pathophysiological mechanism of CSDH to understand why a proposed treatment should be effective. The development of CSDH relies on a complex intertwined pathway of angiogenesis, inflammation, recurrent small bleeds from immature capillaries, exudates, and local coagulopathy (Edlmann et al., 2017;Holl et al., 2018). Second, to prevent a lack of agreement with recommendations, it is essential to provide level I evidence on CSDH treatment through high-quality RCTs. Twenty-six RCTs are currently running or have recently been published on various treatment options, among which steroids, tranexamic acid, statins, surgical techniques, middle meningeal artery embolization, and perioperative care . The third step is to explore the current clinical practice and current attitudes toward CSDH-management among treating physicians. Through this exploration, one can study the outcome expectancy of these treatments and detect familiarity with possible treatments, with possible environmental barriers, and with the inertia of current practice. If major resistance or large differences among treating physicians are found, this might be a barrier when implementing evidence-based treatments.
We conducted an online survey among Dutch neurologists and neurosurgeons. In the Netherlands, neurologists usually diagnose CSDH.
Hereafter, the patient can be treated with an expectant policy, with a nonsurgical treatment (e.g., dexamethasone), or through surgery. If necessary, the neurologist consults a neurosurgeon on further management. They will reach consensus and, if an operation is the preferred option, will transfer the patient to the nearest neurosurgical center. In the end, these two specialisms will decide on the best treatment option for each individual CSDH-patient. Therefore, only these two specialisms were invited to complete this survey, which aims to explore current practice and attitudes toward CSDH-management in The Netherlands.

METHODS
We conducted a national online survey to explore the current expe-

Survey
The online survey was developed by two of the authors (D.C.H. and J.B.) with input from an implementation specialist (E.I.

Analysis
Data were collected from 19 May 2020 to 4 November 2020. All data retrieved through this survey were entered into and analyzed with SPSS 25.0 (SPSS®, Chicago, Il, USA). Standard descriptive statis-tics were used. A minimal statistical level of accuracy of 15% with a 95% confidence level was considered to be acceptable (van Bennekom, 2002). We calculated the statistical accuracy of this survey in both groups using the population size in combination with the percentage of responding neurologists and neurosurgeons. A higher percentage of responses naturally leads to higher accuracy. Also, a larger population size needs fewer responses to achieve the same statistical accuracy as in a smaller population; statistical accuracy and response rate are not linear (Van Bennekom, 2002;Van Bennekom, 2021). Results were described for neurologists and neurosurgeons separately.

RESULTS
A total of 123 responses were received of which 119 full responses from 31 Dutch hospitals (see Figure 1).
The four partial responses were removed from the results. The with a 95% confidence level. With a response of 35% within a population of 153, the statistical level of accuracy in the neurosurgical survey is ±11% with a 95% confidence level (van Bennekom, 2002). Responses received from neurologists and neurosurgeons were largely consistent. Therefore, the differences between the groups were not explicitly included in the written results. These differences between responding neurologists and neurosurgeons can be found in the tables and figures.

Demographics and other respondents' characteristics
A 0-5 years' work experience was seen in 28 (42%) of the responding neurologists and three (6%) of the responding neurosurgeons. A work experience of 20 years or more was seen in 11 (17%) of the responding neurologists and 16 (30%) of neurosurgeons (see Figure 1). No major differences were found related to the years of work experience. Therefore, this has no impact on the presented results.

Opinion on different treatment strategies
A substantial majority of respondents were positive on BHC as CSDH treatment (93.3%); none of the respondents had a negative experience with BHC. More than half of the respondents were positive about a conservative policy in CSDH (56.3%). Around a third of respondents had a positive experience with the use of dexamethasone as primary (30.3%) and additional (33.6%) treatment. Less than 10% had a negative experience with the use of dexamethasone. The vast majority of respondents had (almost) no experience with the use of tranexamic acid, statins, and middle meningeal artery embolization (see Table 1).

F I G U R E 1 Demographics of respondents to a national survey examining views of Dutch neurologists and neurosurgeons on current practice and attitudes toward the management of chronic subdural hematoma
In order to assess the collaboration between neurologists and neurosurgeons, we evaluated the communication or a lack thereof between these specialisms. The majority of responding neurologists indicated they always consult with a neurosurgeon when a CSDH patient has neurological deficits. A third of neurologists stated that the decision to consult a neurosurgeon depends on the severity of CT scan results. Twenty-two percent of neurologists stated they always consult with a neurosurgeon when they have diagnosed patient with CSDH (Table 2).

Treatment choices in four separate CSDH cases
Multiple answers were possible in the presented cases.
In case 1, a vast majority of 83% chose primary BHC. In addition, primary craniotomy was opted by 16 (26%) neurologists and none of the neurosurgeons (see Figure 2).
In case 2, a majority of 65% chose an expectant policy. The secondlargest option with 24% was primary dexamethasone. In addition, 13% of respondents opted for "other" treatment with (additional) antiepileptic drugs (see Figure 2).
In case 3, a majority of 41% chose primary BHC. With 32%, the second-largest option was primary dexamethasone. Twentythree percent of respondents chose an expectant policy (see Figure 2).
In case 4, a majority of 66% chose BHC. The second-largest option with 23% is primary dexamethasone (see Figure 2).
Overall, 20-37% of respondents reasoned the case should be discussed with a neurosurgeon before starting a particular treatment.

Willingness to implement Dutch CSDH RCT results
If the DECSA trial demonstrates that dexamethasone is equally effective or cost-effective compared to BHC, the majority of respondents would be willing to implement the use of dexamethasone (see Figure 3).
Also, the majority of respondents would be willing to use tranexamic acid as the standard of care if a positive effect is shown through the TORCH trial (see Figure 3).

Questions on current clinical practice
The different operative techniques largely correspond among responding neurosurgeons (see Table 3).

DISCUSSION
Worldwide, but also on a national level, there is a broad variation in CSDH-management. The aim of this survey was to make a base- with guideline recommendations, due to lack of applicability or lack of evidence, is the most perceived barrier to guideline adherence (Cabana et al., 1999;Lugtenberg et al., 2009 CSDH is presented by a large variability of symptoms (Kolias et al., 2014). In this survey, we incorporated four fictitious patient cases to evaluate which treatment option was preferred by the respondents in a specific situation. The respondents' answers to these cases represent the consensus and variability in treatment preferences in different situations. The cases described fictitious patients with mild to very severe symptoms having small to large hematomas on a CT scan. Most respondents (83%) chose to perform burr hole craniostomy in the fictitious patient from case 1, who was most severely affected neurologically with a large CSDH. Conservative treatment was chosen by a majority of respondents (65%) for the patient in case 2, who had no neurological symptoms at presentation with a small hematoma. Cases 3 and 4 both concerned a patient with an average-sized CSDH, in both cases combined with the pronation and drift of an arm. In case 4, speech disturbance was additionally present and in this case, burr hole craniostomy was most often chosen (66%). In case 3, without the speech disturbance, the treatment choice was divided over the different treatment options. Burr-hole craniostomy still was the preferred option (41%), but not chosen by the majority of respondents. These findings show that in severe or mild CSDH, most neurologists and neurosurgeons agree on the primary treatment, but in a moderately affected patient it may be more difficult to reach consensus. CSDH remains a complex disease in which a guideline would be beneficial on medical decision making.
The findings in the cases suggest BHC is the most widely used and most accepted treatment option in symptomatic CSDH, which is in line with up-to-date literature (Kolias et al., 2014;Soleman et al., 2017).
A majority of respondents has a positive attitude toward a conservative policy and around a third had a positive experience with the use of dexamethasone as a primary and additional treatment. These numbers were also reflected in the treatment preferences in the presented cases. Ninety-six percent of respondents did not have any experience with middle meningeal artery embolization. Although this procedure has been suggested as an adjuvant and/or alternative intervention for CSDH treatment with a reduced recurrence rate (Catapano et al., 2021;Onyinzo et al., 2021;Shotar et al., 2020), it is not commonly performed in Dutch hospitals as of today. (Peri)operative management largely corresponded among responding neurosurgeons. Remarkably, a majority of responding neurosurgeons prefer a subdural drain to a subperiosteal drain, despite the most recent publications presenting less recurrence when using a subperiosteal drain (Greuter et al., 2020;Pranata et al., 2020;Soleman et al., 2019). This is an illustrative exam- However, even if 844 neurologists did see the invitation, low response rates do not necessarily lead to less accurate measurements (Lindemann, 2019). The neurological response percentage is lower, but the accuracy in both groups matches and is acceptable.
A second limitation, which also concerns the response rate, is that, besides an online survey, not many other survey options were available in 2020 due to the COVID-19 pandemic. We did plan on presenting this survey on national neurosurgical and neurological congresses, in order to increase the response rate and the interest in CSDH-management.
Unfortunately, this was not possible.

Future CSDH-research
It is already known that the intraoperative placement of a subdural drain, remaining in situ up to 48 h, is associated with reduced recurrence and reduced mortality at 6 months (Santarius et al., 2009).
Recently the first adequately sized multicenter RCT studying the role of dexamethasone in CSDH-management was published . In total, 680 patients were randomized for dexamethasone or placebo to test the hypothesis that dexamethasone would improve outcome by reducing the need for surgical intervention.
The dexamethasone group had fewer favorable outcomes and more adverse events than placebo at 6 months, despite fewer reoperations.
It should be noted that the large majority (94%) of patients in this study underwent surgery. Therefore, no definite conclusions could be drawn regarding the effect of dexamethasone as a method of conservative management to avoid surgery . The DECSA trial will provide further insight on this matter . Consensus was reached and their recommendations were translated into a 10-point national guideline (Table 4).
Following their example, we established the Dutch Subdural Hematoma Research group (DSHR) in 2018 (DSHR). The aim of the DSHR is to combine Dutch CSDH-studies and eventually convert the results of (inter)national studies into a widely supported national guideline on the management of CSDH. This baseline inventory is a small but required part of the establishment and implementation of such a guideline.
Once sufficient (inter)national CSDH-RCTs on a large variety of topics are completed , more robust evidence-based decision-making is possible. By that time, we are planning to conduct a national Delphi survey on the establishment and implementation of a national guideline, using this baseline inventory as a stepping-stone in combination with the class I evidence from CSDH-RCTs.

CONCLUSION
In this baseline inventory, we found variation regarding current practice and current attitudes toward CSDH-management in the Netherlands. However, these differences are considered not to be insur-mountable when implementing evidence-based treatments. We advise all CSDH-researchers to establish a national baseline inventory on current clinical practice and current attitudes toward CSDH-treatment.
This is a small but indispensable stepping-stone in the eventual development and implementation of a national guideline.